Paleontology: Ancient Marine Reptiles is a four-lesson course teaching a comprehensive overview of the evolutionary changes that occur when air-breathing terrestrial animals return to water. This course examines the diversity, adaptations, convergence, and phylogenetic relationships of extinct marine reptiles. Students will explore three major groups of marine reptiles: ichthyosaurs, plesiosaurs, and mosasaurs. Watch a preview of the course here: https://uofa.ualberta.ca/courses/paleontology-marine-reptiles

From the lesson

Sauropterygians

Welcome back! We hope you enjoyed the lesson on ichthyopterygians, the first of three in depth explorations of an extinct marine reptile group that we will cover. In this lesson you learned that ichthyosaurs are among the most specialized reptiles that ever lived. They had many adaptations to solving the aquatic problem including large eyes for seeing in deep water, powerful tails to power their thunniform swimming, and two sets of flippers for stability and steering. We also discussed the hypothesis that ichthyosaurs may have overcome the problem of being cold-blooded reptiles living in water by evolving some endothermic capabilities. Even though ichthyopterygians were well adapted for a life in the water, this lineage still went extinct long before the End-Cretaceous Mass Extinction for unknown reasons.
The lesson you are about to start will follow a similar format to lesson 2, but instead of ichthyopterygians, we will be investigating a second major marine reptile lineage: the sauropterygians. These animals shared the seas with the ichthyosaurs for much of their 180 million year existence. You may already know some of the members of this group such as the long-necked elasmosaurs and the massive-jawed pliosaurs such as Liopleurodon. In this lesson we will expand your knowledge of these animals by introducing you to their lizard-like ancestors and a wider variety of the derived members. We will present you with one of the biggest unsolved mysteries surrounding marine reptiles: how did plesiosaurs use their four massive, wing-like flippers to swim? We will also look at how they ate and reproduced, and we will finish by taking you on a worldwide tour of plesiosaur diversity through time.
We hope you enjoy learning about this group of reptiles, who had adaptations so unique that they have never been seen in any other lineage of marine tetrapods.